Photosensitive and thermosensitive elements,compositions and processes

ABSTRACT

A REDUCTONE REDUCING AGENT, SUCH AS AN AMINO HEXOSE REDUCTONE OR AN ANHYDRO DIHYDRO AMINO HEXOSE REDUCTONE, AND AN ACTIVATE TONING AGENT IN A PHOTOSENSITIVE AND THERMOSENSITIVE ELEMENT SUITABLE FOR SO-CALLED DRY PROCESSING WITH HEAT PROVIDE IMPROVED BLACK TONE, INCREASED MAXIMUM DENSITY AND REDUCED BACKGROUND PRINT-OUT. SUCH AN ELEMENT WHICH CONTAINS AN OXIDATION-REDUCTION IMAGE FORMING COMBINATION IN WHICH A REDUCTONE IS EMPLOYED AS A REDUCING AGENT IS ESPECIALLY SUITABLE. THIS CAN BE AN IMAGE REPRODUCTION SHEET IN WHICH A READIATION SENSITIVE HEAVY METAL SALT CAN BE REDUCED TO FREE METAL AOD FORM THE IMAGE COMPONENTS IN AN OXIDATION-REDUCTION REACTION COMBINATION BY PRODUCING A VISIBLE COLOR CHANGE WITH AN ORGANIC SILVER SALT.

United States Patent ABSTRACT OF THE DISCLOSURE 1 A reductone reducing agent, such as an-amino hexose reductone or an anhydro dihydro amino hexose reductone, and an activate toning agent in a photosensitive and thermosensitive element suitable for so-called dry processing with heat provide improved black tone, increased maximum density and reduced background print-out. Such an element which contains an oxidation-reduction image forming combination in which a reductone is employed as a reducing agent is especially suitable. This can be an image reproduction sheet in which a radiation sensitive heavy metal salt can be reduced to free metal and form the image components in an oxidation-reduction reaction combination by producing a visible color change with an organic silver salt.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to photosensitive and thermo:

sensitive elements, compositions and processes for devel-' oping a latent image using certain reducing agents in so-called dry processing with heat, especiallyin such processing employing an oxidation-reduction image forming combination. In one of its aspects it relates to a photosensitive and thermosensitive element employing an oxidation-reduction image forming combination of an oxidizing agent, certain reducing agents, a activator toning agent, and, preferably, a catalyst, e.g. photographic silver halide. In another of its aspects it relates to a photosensitive and thermosensitive composition containing such an oxidation-reduction image forming combination, preferably with a catalyst. A further aspect relates to' a process of developing an image in a photosensitive and ther'mo 3,679,426 Patented July 25, 1972 While many reducing agent have been employed in elements wherein an oxidation-reduction image forming combination of an oxidizing agent and a reducing agent with a toning agent, especially in the presence of a catalyst, some of these have not provided desired black tone orincreased maximum density satisfactorily or reduced background print-out to a desired extent. For example, a hydroquinone reducing agent which has been employed in such a combination has not provided a sufliciently dense black image and moreover the background of the 7 developed image is not desirably clean, that is undesired print-out in the background areas of the print occurs. This is demonstrated in following comparative Example 1.

sensitive element by heating the element which contains the oxidation-reduction image forming combination, as described.

Description of the state of the art It is known to develop a latent image in a photographic silver halide element using a silver halide developing agent in so-called dry processing with heat. The photographic element can contain a silver halide developing agent as well as a stabilizer component. After exposure the resulting latent image can be developed and stabilized by heat-, ing the photographic element. Such a process is described, for example, in U.S. Pat. 3,301,678 of Humphlett et al. issued 'Jan. 31, 1967.

Other methods of so-called dry processing with heat are described, for example, in U.S. Pat. 3,152,904 of Sorensen et al. issued Oct. 13, 1964; French Pat. 1,441,619; Belgian Pat. 705,872; Pat. 2,910,377 of Owen issued Oct. 27, 1959; and U.S. Pat. 3,392,020 of Yutzy et 211. issued July 9, 1968. I g

Accordingly there has been a continuing need to provide reducing agents in photosensitive and thermosensi tive elements employing an oxidation-reduction image forming combination as described which provide blacker tone images having reduced background print-out and improved density.

SUMMARY OF THE INVENTION It has been found according to the invention that in a photosensitive and thermosensitive element, composition, and process employing such an element, employing an oxidation-reduction image forming combination and an activate toning agent, that a reductone reducing agent in such a combination can provide blacker tone images, having reduced background print-out and improved 1 density.

DETAILED DESCRIPTION OF THE INVENTION Photosensitive and thermosensitive elements which are suitable for processing with heat according to the practice of the invention can provide a developed image by physical development, such as described in U.S. Pat. 3,457,075 of: Morgan et al. issued July 22, 1969. Other elements of this type are described, for example, in U.S. Pat. 3,429,706 of Shepard et al. issued Feb. 25, 1969 and U.S. Pat. 3,152,904 of Sorensen et al. issued Oct. 13, 1964. In elements, as described, typically a support is provided with a light stable organic silver salt oxidizing agent, an organic reducing agent, and photographic silver salt, especially silver halide, which provides a photographic and heat-sensitive element. A visible image on the photosensitive and thermosensitive element can be produced within a few' seconds after exposure by heating the element'to moderately elevated temperatures.

Accordingly, one embodiment of the invention is in a photosensitive and thermosensitive element, comprising a support, and.an oxidation-reduction image forming com: bination of (a) an oxidizing agent and (b) a reducing agent with (0) an activator toning agent the improvement comprising a reductone as said reducing agent. This can be, for example, an image reproduction sheet in which a radiation sensitive heavy metal salt can be reduced to free metal and form the image components in an oxidation-reduction reaction combination by producing a visible color change with an organic silver salt.

-A range of reductuone reducing agents is suitable in the practice of the invention. These include, for example, compounds of the formula:

wherein R and R, are each hydrogen, alkyl, especially alkyl containing 1 to 5 carbon atoms suchzas'methyl, ethyl, propyl, and pentyl, or atoms completing a heterocyclie nucleus, as denoted by the broken line in structures I and .ILcontaining a nitrogen atom, preferably containing 4 to 6 carbon atoms in the nucleus, including, for example, a second nitrogen or an oxygen atom, e.g. morpholino, piperazino, pyrrolino, hexamethylene imino, piperidino and the like, and R, is hydrogen or hydroxyl.

V desired anhydro dihydro piperidino hexose, reductone. The

resulting product can be purified if desired such as by recrystallization from a suitable solvent, e.g. ethanol.

The described reductone reducing agents can be employed in the form of a salt, especially an acid salt such as a hydrochloride, sulfate, or the like salt. A reductone reducing agent as employed herein includes such compounds either in salt form or in their nonsalt form.

Suitable reductone reducing agents include thc'following amino hexose reductones, anhydro amino hexose reductones and/or anhydro dihydro amino hexose reductones: v

di-n-butylamino di-n-hexylamino morpholino piperazino di(hexose reductone) pyrrolidino especially D-glucose although other reducing sugars such as D-galactose, D-fructose, L-sorbose or the like can be used. A typical method of preparing the starting amino hexose reductones comprises heating in a-reaction medium, substantially free of water, a hexose reducing sugar and an aliphatic or cyclic secondary amine in the presence of I an acidic reductone formingcatalystic agent such as phosphoric acid, boricacid, acetic acid, succinic' acid or the like. The removal of 3 mols of. water results during the formation-of the amino hexose reductone. The described anhydro amino hexose reductone can -be prepared by heating the hydrochloride salts of the amino hexose reductones further in the presence of strong acids such as sulfuric acid, acetic anhydride, zinc chlorideand the like to remove another mol of water. The described anhydro dihydro hexose reductone compoundscan be prepared from the described anhydro amino reductones by hydrogenation in the presence of a suitable hydrogenation catalyst such as Raney nickel catalyst. The preparation of anhydro dihydro piperidino hexose reductone is typical of the preparation of the class of compounds empolyed in the practice of the invention. One mol of anhydrous D glucose and 1.3 mols of piperidine are stirred together in absolute ethanol under nitrogen for about 15 minutes. The resulting mixture is then heated on a steam bath and stirred until the solution becomes homogeneous. Thena solution of glacial acetic acid in absolute ethanol is added The described reductone reducing agents can be employed' in a photosensitive and thermosensitive element containing a silver-dye complex, a silver halide developing-agent, a source of silver for physical development, as described, especially silver behenate or silver stearate and a binder; especially polyvinyl butyral. Suitable silver-dye complexes are set out in US. Pat. 3,446,619 of Gilman et I a1. issued May 27, 1969. The silver-dye complex is a reaction product of silver ions, e.g. silver nitrate in aqueous solution, with a spectral sensitizing dye which upon exposure to radiation forms active sites for physical development. Typical sensitizing dyes include cyanines, merocyanines, oxonols, hemicyanines, hemioxonols, styryls and benzylidenes. Atypicalphotographic and thermosensitive element containingsuch a silver-dye complex comprises a support havinga layer containing a silvermerocyanine dye complex, silver behenate, a reductone reducing agent, as described, and a binder, such as cellulose acetate, polyvinyl acetate or polyvinyl butyral. The

photographic and thermosensitive element cancontain a' stabilizing agent such as an organic acid stabilizing agent,

e.g. phthalic acid, salicylic acid or benzoic acid.v

The described elements can comprise a silver salt of an organic acid, as an oxidizing agent. The silver salt of the organic acid should be resistant to darkening under .illumination to prevent undesired deterioration of a developed image. An especially suitable class of silver salts of organic acids is represented by the water insoluble,

silver salts of long-chain fatty acids which are'stable to light. Compounds which are suitable silver salts include silver behenate, silver stearate, silver oleate, silver laurate, silver hydroxystearate, silver caprate, silver-myristate, and silver palmitate. Other suitable oxidizing agents are silver S-nitrosalieylaldoxime, silver 5 chlorosalicylaldoxime, silver benzoate, silver phthalazinone, silver benzotriazole, silver saccharin, silver-4'-n-octadecyloirydiphenyl-4 car boxylic' acid, silver ortho-aminobenzoate, silver 'aceta-' midobenzoate', silver furoate, silver camphorate'; silver" p-phenylbenzoate', silver phenyl acetate-silver salicylate,

dropwise to the solution. The resulting solution is stirred silver meta-nitrobenzoate, silverbutyrate; silver terephthalate, silver phthalate, silver acetate, and silver acid phthalate. Oxidizing agents which are" not silver salts can be employed if desired, such as zinc oxide, gold stearate, mercuric behenate, auric behenate and the like;

Other organic reducing agents can be employed in the practice of the invention with the described reductone reducing agents to provide a desired developed image. Such reducing agents are typically silver halide developing agents. Suitable silver halide developing agents or organic reducing agents include, forexample, polyhydroxybenzenessuch as hydroquinone developing agents, e.g. hydroquinone, alkyl-substituted hydroquinones as exemplified by tertiary butyl hydroquinone, methyl hydroquinone, 2,5'-dimethyl hydroquinone and 2,6 dimethyl hydroquinone; catechols and pyrogallol; halo-substituted hydroquinones such as chlorohydroquinone or dichloro-' I those. described in US. Pat. 3,337,342 of Green issued Aug. 22, 1967; hydroxylami'ne developing agents such as N,N-di(2-ethoxyethyl)hydroxylamine; 3-pyrazolidone' de- 'veloping agents such as l-phenyl-3-pyrazolidone and4- methyl-.4-hydroxymethyl-1-phenyl-3-pyrazolidone including those described in British Pat. 930,572 published July 3, 1963; hydroxytetronic acid,.and hydroxytetronimide developing agents; and the like. Combinations of these reducing agents can be employed if desired.

It is preferable to employ a catalyst for the described oxidation-reduction image forming combination. An especially suitable catalyst is photographic silver halide.

"Accordingly a preferred embodiment of the invention is: in a photosensitive and thermosensitive element comprising a support and an oxidation-reduction image forming combination of (a) an oxidizing agent and (b) a reducing agent with (c) an activator toning agent, the improvement comprising a reductone as the reducing agent and a eatalystjespecially photographic silver halide, for the oxidation-reduction image forming combination. The described element can contain a photographic salt asthe described catalyst, especially a photographic silver salt. Suitable photographic silver salts include silver chloride, silver bromide, silver bromoiodide, silver chlorobromoiodide or mixtures thereof. The photographic silver halide can be coarse or fine grain, very fine grain emulsioris being particularly useful. The emulsion containing the photographic silver halide can be prepared by any of the well-known procedures in the photographic art, such as s'ir'igle-jetj emulsions, double-jet emulsions, such as Lipp'mann emulsions, ammoniacal emulsions, thiocyanate or thioether ripened emulsions, such as those described irIfUJS. Pat. 2,222,264 of Nietz et al. issued Nov. 14, 1940; U.S. Pat. 3,320,069 of Illingsworth issued May 15, l967; andfU.S. Pat. 3,271,157 of McBride issued Sept. 6, 1966. Surface image silver halide emulsions can be used or internal image silver halide emulsions such as those described in U.S. Pat. 2,592,250 of Davey et al. issued'Apr. 8, 1952; US. Pat; 3,206,313 of Porter et al. issued Sept. 14, 1965; U.S. Pat. 3,367,778 of Berriman etalQissued Feb. 6, 1968; and U.S. Pat. 3,447,927 of Bacon et al. issued June 3, 1969. If desired, mixtures of surface and internal image silver halide emulsions can be used as described in U.S. Pat. 2,996,382 of Luckey et al. issued Apr. 15, 1961. Negative type emulsions can be used or direct positive silver halide emulsions such as those described in U.S. Pat. 2,184,013 of Leermakersjissued Dec. 19, 1939;.U.S. Pat. 2,541,472 of Kendall et al. issued Feb.v 13, 1951; U.S. Pat..-3,367,778 of Berriman et ,al. issuedFeb. 6, 1968; British. Pat. 723,019; French Pat. 1,520,82.1;;U.S. Pat. 2,563,785 of Ives issued'Aug. 7, 1951; U.S. Pat. 2,466,953 of-Knott et'al. issued Dec. 21, 1968; and U.S. Pat. 2,861,885 of Land issued Nov. 25, 1958. The-silver halide emulsion-can be a regular grain emulsion such as described in Klein and Moisar, Journal of Photographic Science, vol. 12, No. 5, September- October (1964), pp. 242-251. v

The silver halide emulsions employed in the practice of the invention can be unwashed or washed to remove soluble salts. In the latter case the soluble salts can be removed by chill setting and leaching or the emulsion can be coagulation washed.

The silver halide employed in the practice of the invention can be sensitized with chemical sensitizers, such as with reducing agents; silver, selenium or tellurium compounds; gold, platinum, or palladium compounds; or combinations of these. Suitable procedures are described, for example, in U.S. Pat. 1,623,499 of Shepard issued Apr. 5, 1927; U.S. Pat. 2,399,083 of Waller et al. issued Apr. 23, 1946; U.S. Pat. 3,297,447 of McVeigh issued Jan. 10, 1967; and U.S. Pat. 3,297,464 of Dunn issued Jan. 10, 1967.

Photographic silver halide employed in the practice of the invention can be protected against the production of fog and can be stabilized against loss of sensitivity during keeping. Suitable antifoggants and stabilizers, e.g. used alone or in combination include, for example, thiazolium salts; azaindenes; mercury salts as described, for example, in U.S. Pat. 2,728,663 of Allen et al. issued Dec.

27, 1955; urazoles; sulfocatechols; oximes described, for example, in British Pat. 623,448; nitron; nitroindazoles; polyvalent metal salts described, for example, in U.S. Pat. 2,839,405 of Jones issued June 17, 1958; platinum, palladium and gold salts described, for example, in U.S. Pat. 2,566,263 of Trivelli et al. issued Aug. 28, 1951 and U.S. Pat. 2,597,915 of Yutzy et al. issued May 27, 1952.

A photosensitive and thermosensitive element and emulsions described and used in the practice of the invention can contain various colloids alone or in combination as vehicles or binding agents and in various layers. Suitable materials are typically hydrophobic but hydrophilic materials can also be employed. They are transparent or translucent and include both naturally-occurring substances such as proteins, for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccharides such as dextrans, gum arabic and the like; and synthetic polymeric substances such as water-soluble polyvinyl compounds like poly(vinyl pyrrolidone), acrylamide polymers and the like. Other synthetic polymeric compounds which can be employed include dispersed vinyl compounds such as in latex form and particularly those which increase dimensional stability of photographic materials/Suitable synthetic polymers include those described in U.S. Pat. 3,142,586 of Nottorf issued July 28, 1964; U.S. Pat. 3,193,386 of White issued July 6, 1965; U.S. Pat. 3,062,674 of Houck et al. issued Nov. 6, 1962; U.S. Pat. 3,220,844 of Houck et al. issued Nov. 30, 1965; U.S. Pat. 3,287,289 of Ream et al. issued Nov. 22, 1966; and U.S.Pat. 3,411,911 of Dykstra issued Nov. 19, 1968. Eifective polymers include Water insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, and those which have crosslinking sites which facilitate hardening or curing as well as those having recurring sulfobetaine units as described in Canadian Pat. 774,054. Preferred high molecular weight materials and resins include polyvinyl butyral, cellulose acetate butyrate, polymethyl methacrylate, poly (vinyl pyrrolidone), ethyl cellulose, polystyrene, polyvinyl chloride, chlorinated rubber, polyisobutylene, butadiene-styrene copolymers, vinyl chloride-vinyl acetate copolymers, copolymers of vinyl acetate, vinyl chloride and maleic acid, polyvinyl alcohol, and high molecular weight ethylene oxide polymers.

The photosensitive and thermosensitive layers and other layers of an element employed in the practice of the invention and described herein can be coated on a wide variety of supports. Typical supports include cellulose nitrate film, cellulose ester film, poly(vinylacetal) film, polystyrene film, poly(ethylene.terephthalate) film, polycarbonate film and related films or resinous materials, as -well as glass, paper, metal and the like. Typically a flexible support is employed, especially a paper support which can be partially acetylated or coated with baryta and/or an alpha olefin polymer, particularly a polymer of an alpha olefin containing 2 to 10 carbon atoms such as polyethylene, polypropylene, ethylene-butene copolymers and the like.

The photosensitive and thermosensitive and other hardenable layers of an element used in the practice of this invention can be hardened by various organic or inorganic hardeners, alone or in combination, such as aldehydes, and blocked aldehydes, ketones, carboxylic and carbonic acid derivatives, sulfonate esters, sulfonyl halides and vinyl sulfonyl ethers, active halogen compounds, epoxy compounds, aziridines, active olefins, isocyanates, carbodiimides, mixed-function hardeners and polymeric hardeners such as oxidized polysaccharides like dialdehyde starch and oxy-guargum and the like.

The photosensitive and thermosensitive elements used in the practice of the invention can contain antistatic or conducting layers. Such layers can comprise soluble salts such as chlorides, nitrates and the like, evaporated metal layers, ionic polymers such as those described in U.S. Pat. 2,861,056 of Minsk issued Nov. 18, 1958 and U.S.

' situ throughout the 7 a Pat. 3,206,312 of Sterman et al. issued Sept. 14, 1965 or insoluble inorganic salts such as those described in U.S. Pat.3,428,45l of Trevoy issued 'Feb. 18, 1969. The photographic and thermosensitive elements can also contain antihalation materials and antihalation dyes.

The photosensitive and thermosensitive layers or other layers employed in the practice of the invention can contain plasticizers and lubricants. Suitable plasticizers and lubricants include, for example polyalcohols such as glycerin and diols described, for example, in U.S. Pat. 2,960,404 of Milton et al. issued Nov. 1,1966; fatty acids or esters such as those described in U.S. Pat. 2,588,765 of Robijns issued Mar. 11, 1952; U.'S. Pat. 3,121,060 of Duane issued Feb. 11, 1964; and silicone resins such as those described in British Pat. 955,061.

The photosensitive and thermosensitive layers or other layers employed in the practice of the invention can contain surfactants such as saponin; anioniccompounds such as alkyl aryl sulfonates described, for example, U.S. Pat. 2,600,831 of Baldsiefeu issued June 17, 1962; amphoteric compounds such as those described in U.S. Pat. 3,133,816 of Ben-Ezra issued May 19, 1964; and 'adducts of glycidol and an alkyl phenol such as those described in British Pat. 1,022,878. If desired, the photosensitive and thermosensitive elements employed in the practice of the invention can' con-' tain matting agents such as starch, titanium dioxide, zinc oxide, silica, polymeric beads including beads described, for example, in U.S. Pat. 2,992,101 of Jelley et a1. issued July 11, 1961 and U.S. Pat. 2,701,245 of Lynn issued Feb. 1, 1955. v

' The photosensitive and thermosensitive elements employed in the practice of the invention can contain brightening agents including stilbenes, triazines, oxazoles, and coumarin brightening agents. Water-soluble brightening agents can be used such as those described in German Pat. 972,067 and U.S. Pat. 2,933,390 of McFall'et al.

isued Apr. '19, 1960 or dispersions of brighteners can be used such as those described in German Pat. 1,150,274;

U.S. Pat. 3,406,070 of Oeti'ker et al. issued Oct. 15, 1968;

and French IPat. 1,530,244.

various layers including the photographic and therntbsen'sitivedayers of an element employed in the practice of the invention can contain light-absorbing materials and 'dilter dyes such as those described in U.S. Pat. 3,253,921 of Sawdey issued May 31, 1966; U.S. Pat. 2,274,782 of Gaspar issued Mar. 3, 1942; U.S. Pat. 2,527,583 of Silberstein et a1. issued Oct. 3 1, 1950; and US. Pat. 2,956,879 of Van Campen issued Oct. 18,1960.

If desired, the dyes can be mordanted, for example, as

. I: desired, the photographic silver halide can be prepared in situ in the photosensitive and thermosensitive coatings of'an element employed in the practice of the invention. -Such a method is described, for example, in US. Pat. 3,457,075 0 1: Morgan et al. issued July 22, 1969. For example, a dilute solution of a halogen acid such as hydrochloric acid can be applied to the surface of a thin coating containing an organic sillver salt, such as silver behenate, on a suitable substrate followed by removal of the solvent if desired. Silver halide is thus formed in surface of the coating of the organic silver salt.

photographic silver halide can be prepared on the halide. A suitable reaction "medium includes water 'or other solutions which do not interfere with the reaction.

Spectral sensitizing dyes can be used conveniently to confer additional sensitivity to the elements employed in the practice of the invention. For instance, additional spectral sensitization can be obtainedby'treating the silj ver halide with a solution of a sensitizingdy'e inan'or ganic solvent or the dye can be added in the form of a dis persion as described in British Pat. 1,154,781. For

optimum results the dye can either be added to the emulsion as a final step or at some earlier stage.

Sensitizing dyes useful in sensitizing silver halide are described, for example, in U.S. Pat. 2,526,632 of Brooker et a1. issued Oct. 24, 1950; U.S. Pat. 2,503,776 of Sprague issued Apr. 11, 1950; U.S. Pat. 2,493,748 of Brooker et al. issued Ian. 10, 1950; and U.S. Pat-3,394,486 of'Taber et al. issued May 21, 1968. Spectralsensitiziers which can be used include the cyanines, merocyanines, complex (trif nuclear or tetranuclcar) merocyanines, complex (tri-'- nuclear or tetrauuclear) cyanines, holopolar cyanines,

styryls, hemicyanines, such as enamine hemicyanines, oxonols and hemioxonols. Dyes of thefcyanines classes can contain such basic nuclei-as the thiazolines, oxazolines, pyrrolines, pyn'dines, oxazoles, thiazoles, selenazoles, and imidazoles. Such nuclei can-contain alkyl," alkylene, hydroxyalkyl, sulfoalkyl, carboxyalk'yl, aminoalkyl, and enamine'groups that can be fused to carbocyclic or heterocyclic ring systems either unsubstituted or substituted with halogen, phenyl, alkyl, haloalkyl, cyano,or alkoxy groups. The dyes can be symmetrical or unsymmetrical and can contain alkyl, phenyl, enamine or hetcrocyclic substituents on the methine or polymethine chain.

The merocyanine dyes can contain the basic nuclei-dc scribed as well as acid nuclei. such as thiohyd'anatoins, rhodanines, oxazolidenediones, 'thiazolidenediones," bar bituric acids, thiazolineones, and .malononitrile." These acid nuclei can be substituted with alkyl, alkylene, phenyl; carboxyalkyl, sulfoalkyl, hydroxy'alkyl, alkoxyalkyl, alkylamino groups, or heterocyclic nuclei." Combinations of these dyes can be used, if desired. In addition, super sensitizing'addenda which do not absorb' visible be included such as, for instanceyascorbic" acid deriva-- tives, azaindenes, cadmium salts, and organic 'sulfonic' acids as described in U.S. Pat. 2,933,390 of McFall et al. issued Apr. 19, 1 960 and U.S. Pa t. 2,937,089 of Jones the practice of the invention. The desired concentration.

will be influenced by the desired spectral sensitivity, other components in the system, the desired image,,processing conditions and the like. Typically a concentration'of the described sensitizing dye is about 0.05 to about gram per square foot of the described photographicf' and persquare foot of dye being employed. I It is necessary to employ a so-calledwactivator toner in the described photosensitive and thermosensitive elements the'rmosensitive element, usually "about. 0 .1

according to the invention in order to obtain a desirable black image. Various toners can be employed for this purpose. Typically a heterocyclic organic toning agent containing at least two hetero atoms in the heterocyclic ring of which at least one is a nitrogen atom is employed.

These are described, for example, in U.S. Pat. 3,080,254 of Grant issued Mar. 5, 1963. Suitable toners include, for example, phthalazinone, phthalic anhydride, 2-acetyl phthalazinone, and 2-phthalyl phthalazinone. Other suitable toners are described, for example, in U.S. Pat. 3,446,648 of Workman issued May 27, 196 9.

Another embodiment of the invention is: in a photosensitive and thermosensitive composition comprising an oxidation-reduction image forming combination of (a) .an oxidizing agent and (b) a reducing agent and (c) an activator toning agent the improvement comprising a reductone as the reducing agent. A reductone reducing agent is suitably one within Structures I and II, as described. An especially suitable oxidation-reduction image forming combination is (a) silver behenate, and (b) an anhydro dihydro amino hexose reductone.

. This composition typically contains a catalyst for the oxidation-reduction image forming combination. As described, photographic silver halide is especially suitable as the catalyst. I f

e The concentration of catalyst is typically up to about 10 mol percent relative to the described oxidizing agent, e.g. silver behenate. That is, for example, the described composition can contain to about 10 mol percent of catalyst, especially photographic silver halide, relative to oxidizing agent.-

A suitable concentration .of oxidizing agent is that which provides about 20 to about 400 milligrams of silver salt per square foot of support when the composition is coated on a support to provide a photosensitive and thermosensitive element, as described.

A suitable concentration of reductone reducing agent, as described, is usually about 5 to about 100 milligrams of reductone per square foot of support.

The oxidizing agent and reducing agent are usually employed in about a 1:1 molar ratio.

A suitable composition within this embodiment is a photosensitive and thermosensitive emulsion comprising:

(a) silver behenate, V v

(b) a reductone reducing agent, asdescribed, (clphotographic silver halide,

(d) polyvinyl butyral, and

(e) an activator toningagent.

Another embodiment'of the invention is a process of developing a latent image in a photosensitive and thermosensitive element comprising a support and .an'oxidationreduction image forming combination of (a) an oxidizing agent and (b) a reducing agent which comprises a reductone as described, and (c) an activator toning agent comprising heating the element to about 70 C. to about 250 C., e.g. about 80 C. to about 150 C.

A temperature range of about 70 C. to about 250 C., typically about 80 C. to about 150 C., is suitable. By increasing or decreasing the time of heating, a higher or lower temperature within the described range can be employed. A developed and stable image usually results within about 1 second to about 60 seconds, e.g. about 1 second to about 20 seconds.

Processing is usually carried out under ambient conditions of temperature, pressure and humidity. Temperature, pressures and humidity outside normal atmospheric conditions can be employed if desired, however, normal atmospheric conditions are preferred.

In some cases, if desired, an element can be prepared wherein the described catalyst, e.g. photographic silver halide, can be in one layer and other components in other layers of the element. For example, an element according to the invention can comprise a support, a layer containing photographic silver halide and a layer 10 contiguous to the silver halide containing the described oxidation-reduction image forming composition and an activator toning agent. Various means can be employed in providing the necessary heating. The described element can be brought into contact with a simple hot plate, iron or the like.

Other addenda useful in photosensitive and thermosensitive elements can be employed in elements, compositions and processes according to the practice of the invention. Such elements and addenda are described, for example, in British Pat. 1,161,777 published Aug. 20, 1969 and U.S. Pat. 3,152,904 of Sorensen et al. issued Oct. 13, .1964.

If desired, the described photosensitive and thermosensitive elements and compositions employed in the practice of the invention can comprise a silver halide developme'nt'inhibitor releasing compound, such as a developing agent or coupler containing a development inhibitor moiety which. is releasable upon heating. A typical silver halide development inhibitor releasing compound contains a heatreleasable phenylmercaptotetrazole moiety, such as l-hydroxy-4-(l-phenyl-S-tetrazolylthio)-2-(2-ntetradecyloxy)-naphthanilide or a (l-phenyl-S-tetrazolylthio) hydr'oquinone silver halide developing agent. Such compounds are described, for example, in U.S. Pat. 3,227,554 of Barr et al. issued Ian. 4, 1966, which relates to. development inhibitor releasing couplers and U.S. Pat. 3,379,529 of Potter et al. issued Apr. 23, 1968, which relates to development inhibitor releasing silver halide developing agent.

The following examples are included for a further understanding of the invention.

EXAMPLE 1 This is a comparative example. The following components are thoroughly mixed in a blender to form a silver salt dispersion:

Polyvinyl butyral g 10.0 Silver behenate g 28.0 Methanol ml 133.0 Acetone ml 133.0 Toluene ml 133.0

This is designated as silver salt dispersion A. Ten (10) milliliters of silver salt dispersion A, as described, ismixed with the following components:

Trimethyl-(lQphenyl 5 tetrazolylthioyhydroquinone (2.0% by weight in acetone) 15.0

The latter two compounds contain a l-phenyl-S-tetrazolylthio moiety which is released upon heating. The hydroquinone moiety of the last compound is a reducing agent.

The resulting composition is coated on a paper support having a resin coating of polyethylene. The composition is coated on the support at 5 to 10 milliliters per square foot. The resulting coating contains 15 to 30 milligrams of silver per square foot.

The resulting photosensitive and thermosensitive element is sensitometrically exposed with ultraviolet light for 5 seconds. The latent image is developed by holding the element in contact with a metal block at C. for 10 to 45 seconds.

A developed image is produced.

For evaluation of the resulting developed image a rating system is employed wherein the image is assigned a rating from 1 to 5. A rating of 1 represents a dark black image with high resolution, i.e. a sharp image.

, mlylthio)-hydroquinone of Example 1.-

A rating of represents a brown to grayimage with poor resolution. The ratings between 1 adj represent decreasing saturation in image density andloss of image sharpness. Employing this rating scale the developed image of Example 1 is assigned a rating of 4. I g

EXAMPLE 2 v This illustrates the invention. 1;

The procedure set out in Example 1 isrepeated with the exception that 15 milliliters of a solution of 1.0%

by weight of dimethylamino hexose reductonein acetone EXAMPLE 3 This further illustrates the invention.

the exception that milliliters of a solution of 1.0%

I by weight of piperidino hexose reductone'is employed in place of the trimethyl-(l-phenyl-S-tetrazolylthio)-hydroquinone of Example 1.

The resulting element is sensitometricallyexposedand the resulting latent image is developed by heating the same manner as in Example 1.

The resulting developed image is given a rating of l employing the rating scale set out in Example 1. The developed image has a much denser, blacker tone than the image produced in Example 1. The image has a cleaner background also.

EXAMPLES 4-8 v Similar results to those set out in Example 3 are ob-' tained employing the following reductones in place of piperidino hexose reductone: p f f Example 4.Anhydro dihydro dimethylamino hexose reductone.

' Example ,5.Anhydro dihydromorpholino hexose .re-

* ple 6.-Anhydro dihydro di-n-butyl amino hexose reductone. I A

Example 7.-Anhydro piperidinohexose reductone. Example 8.-'Anhydro dihydro piperidino hexose reductone.

EXAQ mm I The procedure set out in Example 2 is repeated with the exception that the composition containing the re- .ductone, as described,- is coated on terephthalate) film support.

Similar results to Example 2 are obtained. EXA MPLE 10' The procedure set out in Example 2 is repeated v vith the exception that the sensitometric exposure is with tungsten light rather than ultraviolet 1ight.,

a Similar results to Example 2 are obtainedi 1 7 This example demonstrates the desirability of having a catalyst, e.-g. silver halide, present in a photosensitive a poly (ethylen'e 'and thermosensitive element employed in-the practice ot the invention. V a The silver salt dispersion containing silver behenate asset but in Example 1 is employed in" this example.

' coating of polyethylene as describedin Example 1. The

. v 12 a Ten (10 milliliters of the described silver salt dispersion A is mixed with the following components:

2-mercapto-5-pheny1-1,3,4-oxadiazole (1.0% by" j weight in acetone) 5Z0 1-hydroxy-4-(l-phenyl 5 .tetrazolylthio)-2-(2' -p- Q tetradecyloxy)-naphthanilide (2.0% by weight in v jacetone) 20.9 Piperidino hexose reductone (1.0% by weight in acetone) 15.0

This is coated on a paper support having a" resin composition is coated on the support at 5 to 10 milliliters per square foot.--The coating contains l5 to 30 of silver-per square foot. 1 r K The resultinggelement is, sensitometrically expoud i to ultraviolet light for 2 minutes. The element is thenheated on a hot metal block for 30 seconds at a temperature of C. 4. I

An image is. developed having a brown tone and an ivory. background. v r yIt is tobe noted that compared to the image .developed in this example the presence of ammoniumiodide .in

I Example 3, which is believed to provide -,silver iodide The procedure set out in Example 1 is repeated with in situ, provides a much :denser, blacki-ma'gewith shorter exposure time. 4 W v I p EXAMPLE 12 This' exampleIfurtherillustrates the invention.' I v; The procedure set outin Example 11 is repeated with the exception that 3.0 milliliters of salicyclic' acid (2.0%

by weight in acetone) is addedto the coating composi tion described in Example 11. r V p v The resulting developed image has excellent" resolution and density, but has a brown tone with a tan backf ground. r t a. H EXAMPLE 13 g This is a comparative example illustrating the need for an activator toning agent in an element employed in-the practice of the invention.

The procedure set-out 1n Example 11 is with the exception that 2-me'rcapto 6-phenyl-1,3,4 oxadiazole is omitted. a

After heating theelement for 30 on a hot metal block of 85 C., no image is observed. y

The invention has been described in detail with I lar reference to preferred embodiments thereof, but it will be understood that variations and modifications be elfected within the spirit and scope'of .the invention. 1.

Iclaimz' t I 1. In a photosensitive and thermosensitive element comprising element comprising a support and an oxidation-reduction image-forming combination of (a) an'oxidizing agent and (b) a reducing agent with (c) activator-toning agent and (d) a catalyst for said image-forming com bination, the improvement comprising an amino reductoneas'said reducingagent. s v 1 -zp An'element as in claim 1 wherein said ductone is an amino hexose reductone'ofthe formulas;

.Rs CH1 I I, v v

(m E 2 on 13 wherein R and R are each hydrogen, alkyl containing 1 to carbon atoms, or taken together, are atoms complet ing a heterocyclic nucleus, containing 4 to 6 carbon atoms in said heterocyclic nucleus, R is hydrogen or hydroxyl.

3. An element as in claim 1 wherein said oxidizing agent is a silver salt of a fatty acid.

4. An element as in claim 1 wherein said oxidizing agent is silver behenate.

5. An element as in claim 1 wherein said catalysts is photographic silver halide.

6. An element as in claim 1 comprising a support,

(a) silver behenate,

(b) an anhydro dihydro amino hexose reductone,

(c) photographic silver halide and a binder.

7. An element as in claim 1 comprising a support,

(a) silver behenate,

(b) anhydro dihydro pyrrolidino hexose reductone or anhydro dihydro piperidino hexose reductone,

(c) a photographic silver halide, and

(d) polyvinyl butyral.

8. In a photosensitive and thermosensitive composition comprising an oxidation-reduction image-forming combination of (a) an oxidizing agent and (b) a reducing agent with (c) an activator toning agent and (d) a catalyst for said image-forming combination, the improvement comprising an amino reductone as said reducing agent.

9. A composition as in claim 8 wherein said amino reductone is an amino hexose reductone of the formula:

wherein R and R are each hydrogen, alkyl containing 1 to 5 carbon atoms, or taken together, are atoms complet ing a heterocyclic nucleus containing 4 to 6 carbon atoms in said heterocyclic nucleus, R is hydrogen or hydroxyl.

10. A composition as in claim 8 comprising (a) silver behenate, and

(b) an amino hexose reductone.

11. A composition as in claim 8 comprising a catalyst for said oxidation-reduction image-forming combination.

12. A composition as in claim 8 wherein said catalyst is photographic silver halide.

13. A process of developing a latent image in an exposed photosensitive and thermosensitive element comprising a support and an oxidation-reduction image-forming combination of (a) an oxidizing agent and (b) a reducing agent which comprises an amino reductone with (c) an activator toning agent and (d) a catalyst for said image-forming combination comprising heating said element to about 70 C. to about 250 C.

14. A process as in claim 13 wherein said element comprises a support and an oxidation-reduction image forming combination of (a) silver behenate and (b) an amino hexose reductone and (c) photographic silver halide.

15. In a photosensitive and thermosensitive element 14 comprising a support and an oxidation-reduction imageforming combination of (a) a silver salt oxidizing agent and (b) a reducing agent which (c) an activator-toning agent and (d) photosensitive silver halide, the improvement wherein said reducing agent comprises an amino hexose reductone of the formula:

wherein R and R are each hydrogen, alkyl containing 1 to 5 carbon atoms, or taken together, are atoms completing a heterocyclic nucleus containing 4 to 6 carbon atoms in said heterocyclic nucleus; R is hydrogen or hydroxyl.

17. A process of developing a latent image in an exposed photosensitive and thermosensitive element comprising a support and an oxidation-reduction image-forming combination of (a) a silver salt oxidizing agent and (b) a reducing agent comprising an amino hexose reductone of the formula:

R. on.

wherein R and R, are each hydrogen, alkyl containing 1 to 5 carbon atoms, or taken together, are atoms completing a heterocyclic nucleus containing 4 to 6 carbon atoms C. to about 250' C.

1 6 References Cited UNITED STATES PATENTS 3,457,075 Morgan 96,-114 .1

OTHER REFERENCES Chemical Abstracts, Chemical Sensitizers and Ripening Retarders on Silver Bromide Sols, vol. 51, 1957, 855909).

Chemical Abstracts, Color Diffusion-Transfer Processj vol. 64, 1956,9149 a NORMAN G. TQRCHIN, Primary Eimminer I R. HIGHTOWER, Assistant Examiner Us. 01. X.R.

mg UNITED STATES PATENT CFFICE I CERTIFICATE OF CORREC'HQN Patent No. 3, 79,426 Dated July 25, 1972 Inventor(s) Mary J. Youngquist It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 15, "activate" should read --activator--.

Column 2 line'l, "agent" should read ---agents---. Line 26, "activate should read --activator---. Line 59, "reductuone" should read .'---reductone'- Column 3, line 1, before "(11)" insert -or--. Line 36, "used" should read --tones---'- and "starting" should read ---described---.

Column 5, line L8 "2,LL66,953" should read --2,LL56,953--. Line 67, 3,297,464" should read ---3, 97,

Column,7, line 56, "Beguim". should read --Beguin-.

Column 10, line 50, wegiht" should read --weight-. v

Column 12, line 6, "p-" should read -n Line 53, elete "element comprising".

Column 13, line 9, "catalysts" should read -catalyst-.

Page 2 UNITED STATES PATENT UFFECE I CERTIFICATE OF CORRECTKQN Patent No. 3, 79,4 Dated uly 25, 1972 Inventor(s) MaryJ. Youngquist It is certified that error appear-s in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

00111111111 1, line 3, "which" should read ---with. Lines 35- LO, that part of the formula reading "CH" should read 'CH3. I

Column 16, the first reference cited "3,691,589 should read ---2,69l,589--.

Signed and sealed this 29th dayof May 1973.)

Attest;

EDWARD M.FLET H R,J ROBERT GOTTSCHALK Att$-tll lg Offlcer Commissioner of- Patents 

